For the production of electronic or optoelectronic semiconductor devices, it would be desirable to have substrates available with a cubic lattice structure and a lattice constant that lies between the lattice constants of GaAs and GaP. Such substrates could be used for the epitaxial growth of III-V semiconductor layers or II-VI semiconductor layers, in particular ternary or quaternary compounds, which have a lattice constant between those of GaAs and GaP and have not previously allowed themselves to be produced with adequate quality, or only by comparatively great expenditure on production.
However, elementary or binary semiconductor materials with a lattice constant that lies between those of GaAs and GaP are not known. Furthermore, ternary semiconductor compounds such as GaAsP or InAlGaP cannot be produced by the known crystal growing methods, or only with poor crystal quality directly as substrate materials.
One approach to solving this problem is to grow a comparatively thick buffer layer, for example of GaAsP, on a GaAs substrate, in order in this way to produce a quasi-substrate with a lower lattice constant than GaAs. In this case, however, comparatively great layer thicknesses of typically more than 10 μm are required in order to reduce the crystal defects, in particular dislocations, that are caused by the lattice mismatch between the substrate and the buffer layer in the direction of growth of the buffer layer in such a way that epitaxial growth of further semiconductor layers on the surface of the buffer layer is possible with adequate quality.
Furthermore, it has been found to be disadvantageous that a semiconductor wafer provided with such a buffer layer has comparatively great warpage, which is caused by incomplete relaxation of the buffer layer and the resultant layer stress.